Nvidia Corporation

Gary C King

Michael J M Toksvig

Edward Anthony Hutchins

Steven E Molnar

Christopher D S Donham

Walter E Donovan

Douglas H Rogers

David Kirk McAllister

Douglas Sim Dietrich

Luke Y Chang

Mark J Kilgard

Brian Keith Cabral

James Michael O'Connor

John H Edmondson

Bengt-Olaf Schneider

Peter B Holmqvist

Methods and systems for decompressing data are described. The relative magnitudes of a first value and a second value are compared. The first value and the second value represent respective endpoints of a range of values. The first value and the second value each have N bits of precision. Either the first or second value is selected, based on the result of the comparison. The selected value is scaled to produce a third value having N+1 bits of precision. A specified bit value is appended as the least significant bit of the other (non-selected) value to produce a fourth value having N+1 bits of precision.

Data decompression with extra precision

Image-based data, such as a block of texel data, is accessed. The data includes sets of color component values. A luminance value is computed for each set of color components values, generating a range of luminance values. A first set and a second set of color component values that correspond to the minimum and maximum luminance values are selected from the sets of color component values. A third set of color component values can be mapped to an index that identifies how the color component values of the third set can be decoded using the color component values of the first and second sets. The index value is selected by determining where the luminance value for the third set lies in the range of luminance values.

Compressing image-based data using luminance

A computer-implemented graphics system has a mode of operation in which primitive coverage information is generated by a rasterizer for real sample locations and virtual sample locations for use in anti-aliasing. An individual pixel includes a single real sample location and at least one virtual sample location. If the coverage information cannot be changed by a pixel shader, then the rasterizer can write the coverage information to a framebuffer. If, however, the coverage information can be changed by the shader, then the rasterizer sends the coverage information to the shader.

Writing coverage information to a framebuffer in a computer graphics system

The boundary of a surface can be represented as a series of line segments. A number of polygons are successively superimposed onto the surface. The polygons utilize a common reference point and each of the polygons has an edge that coincides with one of the line segments. Coverage bits are associated with respective sample locations within a pixel. A value of a coverage bit is changed each time a sample location associated with the coverage bit is covered by one of the polygons. Final values of the coverage bits are buffered after all of the polygons have been processed. The values of the coverage bits can be used when the surface is subsequently rendered.

Using coverage information in computer graphics

Methods and systems for compressing and decompressing data are described. A first value of N+1 bits and a second value of N+1 bits are reduced to strings of N bits each. The first and second strings of N bits are stored in a particular order relative to one another in a compression block. The particular order in which the first and second strings of N bits are stored in the compression block is used to derive a bit value that is then used in combination with one of the strings of N bits to reconstruct that string as N+1 bits.

Two component texture map compression

A computer-implemented graphics system that includes a rasterizer and a shader has a mode of operation in which primitive coverage information is generated for real sample locations and virtual sample locations for use in anti-aliasing. An individual pixel includes a single real sample location and at least one virtual sample location. In some instances, a primitive may cover only virtual sample locations and does not cover a real sample location. These instances can be identified in the coverage information sent from the rasterizer to the shader, so that the shader can determine whether or not it can write color information, depth information and/or stencil information for the real sample location to a framebuffer.

Shader that conditionally updates a framebuffer in a computer graphics system

Embodiments of the present invention sets forth a method and system for reducing memory bandwidth requirements for an anti-aliasing operation. The first virtual coverage information for a pixel involved in an anti-aliasing operation is maintained in memory. If a certain operating condition of the anti-aliasing operation deterministically implies the second virtual coverage information for this pixel, the second virtual coverage information, as opposed to the first virtual coverage information, is used in the anti-aliasing operation. In such situations, since the virtual coverage information is implied, it does not have to be accessed from memory, thereby improving overall system performance.

Method and system for reducing memory bandwidth requirements in an anti-aliasing operation

A computer-implemented graphics system has a mode of operation in which primitive coverage information is generated for real sample locations and virtual sample locations for use in anti-aliasing. An individual pixel includes a single real sample location and at least one virtual sample location. A block of real sample locations can be selected to delineate and encompass a region containing a number of virtual sample locations. Pixel attribute values (e.g., z-depth or stencil values) associated with the block of selected real sample locations can be used to associate each virtual sample location within the region with one of the selected real sample locations. The virtual sample location assumes the pixel attribute value of the real sample location with which it is associated.

Selecting real sample locations for ownership of virtual sample locations in a computer graphics system

In a raster unit of a graphics processor, a method for bounding region accumulation for graphics rendering. The method includes receiving a plurality of graphics primitives for rasterization in a raster stage of a graphics processor and rasterizing the graphics primitives to generate a plurality pixels related to the graphics primitives and a plurality of respective bounding regions related to the graphics primitives. Upon receiving an accumulation start command, the bounding regions are accumulated in an accumulation register. The accumulation continues until an accumulation stop command is received. The operation results in an accumulated bounding region. Access to the accumulated bounding region is enabled to facilitate a subsequent graphics rendering operation.

Bounding region accumulation for graphics rendering

Data that includes an encoded version of sets of color component values for a block of texels is accessed. The encoded version includes a first set of color component values selected from a pre-encoded version of the sets and a second set of color component values selected from the pre-encoded version of the sets. The first set and the second set correspond to endpoints of a range of colors. The encoded version further includes index values associated with the texels. The first set and the second set and an index value associated with a texel are used to decode a third set of color component values that describes a color for the texel. The index value indicates how to determine the third set using the first set and the second set.

Decompressing image-based data compressed using luminance

Circuits, methods, and apparatus that reduce the amount of data transferred between a graphics processor integrated circuit and graphics memory. Various embodiments of the present invention further improve the efficiency of blenders that are included on a graphics processor. One embodiment provides for the storage of a reduced number of subsamples of a pixel when the storage of a larger number of subsamples would be redundant. The number of subsamples that are blended with source data are compressed, thereby reducing the task load on the blenders increasing their efficiency. These methods can be disabled to avoid errors that may arise in certain applications.

Optimized alpha blend for anti-aliased render

A graphics system has a mode of operation in which real samples and virtual samples are generated for anti-aliasing pixels. Each virtual sample identifies a set of real samples associated with a common primitive that covers a virtual sample location within a pixel. The virtual samples provide additional coverage information that may be used to adjust the weights of real samples.

System and method for virtual coverage anti-aliasing

A system, apparatus, and method are disclosed for modifying positions of sample positions for selectably oversampling pixels to anti-alias non-geometric portions of computer-generated images, such as texture, at least in part, by shifting shading sample positions relative to a frame of reference. There is generally no relative motion between the geometries and the coverage sample positions. In one embodiment, an apparatus, such as a graphics pipeline and/or a general purpose graphics processing unit, anti-aliases geometries of a computer-generated object. The apparatus includes at least a texture unit and a pipeline front end unit to determine geometry coverage and a subpixel shifter to shift shading sample positions relative to the frame of reference. The apparatus can receive subpixel shifting masks to select subsets of shading sample positions. Each of the shading sample positions is shifted to a coverage sample position to reduce level of detail ('LOD') artifacts.

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San Jose, CA, United States of America

Gary C King